PPVK - Vision2

Question 1

Acuity

Answer 1

the smallest spatial detail that can be resolved.

Question 2

Snellen E test

Answer 2

is a visual acuity test used to measure how well a person can see at a distance. It’s a variation of the standard Snellen eye chart, but instead of using letters, it uses the letter “E” in different orientations (flipped in various directions: up, down, left, right).

Question 3

What does a smaller visual angle indicate about vision?

Answer 3

The smaller the visual angle at which you can identify a cycle of a grating, the better your vision

Question 4

What is the center-to-center separation of cones in the fovea?

Answer 4

0.5 minutes per arc

Question 5

What does the acuity limit of 1 minute of arc indicate?

Answer 5

means we need two cones per cycle to perceive the grating accurately.

Question 6

How are rods and cones arranged in the periphery?

Answer 6

Rods in the periphery are physically more tightly packed than cones

Question 7

How do receptors in the periphery interact with ganglion cells?

Answer 7

In the periphery, many receptors converge on each ganglion cell.

Question 8

horizontal and vertical asymmetry

Answer 8

Better acuity at fixed distance along the horizontal midline than the vertical
midline

Question 9

vertical meridian asymmetry

Answer 9

Better acuity at fixed distance below the midline of the visual field than above

Bolja oštrina na fiksnoj udaljenosti ispod središnje linije vidnog polja

Question 10

_____vision is considerably slower, than ______ vision

Answer 10

central, peripheral

Question 11

Why do foveal cones have slower responses compared to peripheral cones?

Answer 11

Foveal cones have longer axons than peripheral cones. The longer axons transmit slow signals better than fast ones, resulting in slower response times.

Question 12

What advantage does the slower response of foveal cones provide?

Answer 12

increases their reliability by integrating inputs over a longer period.

Question 13

Spatial frequency

Answer 13

cycles of a grating per unit of visual angle (in degrees) or the number of times a pattern repeats per unit area.

Question 14

Are pure sine wave gratings common in the real world?

Answer 14

No, pure sine wave gratings are rare in the real world. Patterns of stripes with fuzzy boundaries, such as trees in a forest or books on a bookshelf, are much more common.

Question 15

How does the visual system process images? (Fourier analysis)

Answer 15

The visual system breaks down images into a vast number of components, each represented as a sine wave grating with a particular spatial frequency. This process is called “Fourier analysis.”

Question 16

How do center-surround receptive fields respond to sine wave patterns?

Answer 16

with different spatial frequencies

Question 17

Lateral geniculate nucleus (LGN)

Answer 17

The LGN is a structure in the thamalus part in the midbrain where axons of retinal ganglion cells synapse. There is one LGN in each cerebral hemisphere, and it acts as a relay station on the way from the retina to the visual cortex.

Question 18

How does the LGN process visual information from both eyes?

Answer 18

Each layer of the LGN receives input from one or the other eye. Layers 1, 4, and 6 of the right LGN receive input from the left (contralateral) eye, while layers 2, 3, and 5 receive input from the right (ipsilateral) eye.

Question 19

Magnocellular cells (in LGN)

Answer 19

large cells, bottom two layers
receive input from M ganglion cells
respond best to large, fast-moving objects

Question 20

Parvocellular cells (in LGN)

Answer 20

smaller cells, top four layers
receive input from P ganglion cells
respond best to fine spatial details of stationary objects

Question 21

Koniocellular cells (in LGN)

Answer 21

→very small cells in between the magnocellular and parvocellular sections
→we are still not entirely sure what these cells do

Question 22

The striate cortex?

Answer 22

-> (also known as V1 or the primary visual cortex)
-> it is the part of the brain responsible for the initial processing of visual information.
-> It is located in the occipital lobe, at the back of the brain, and is the first cortical area to receive visual input from the lateral geniculate nucleus (LGN) of the thalamus.

Question 23

Two important features of striate cortex

Answer 23

1)Topographical mapping
2)Cortical magnification
- Dramatic scaling of information from different parts of visual field

Question 24

Visual crowding

Answer 24

→stimuli that can be seen in isolation in peripheral vision become hard to discern when other stimuli are nearby
(podražaje koji se mogu vidjeti izolirano u perifernom vidu postaje teško razaznati kada su drugi podražaji u blizini)

Question 25

Cells in the _______ respond best to ________

Answer 25

striate cortex, bars of light

Question 26

Orientation selectivity

Answer 26

neurons in striate cortex respond most to bars of certain orientations

Question 27

Elongated receptive fields in striate cortex

Answer 27

a neuron that responds to oriented bars of light might receive input from several retinal ganglion cells

Question 28

Many cortical cells respond well to?

Answer 28

moving lines, bars, edges, certain motion directions, gratings

Question 29

Striate cortex functions like a ______ for the portion of the _____ that exits the _________

Answer 29

filter, image, cell

Question 30

How do receptive fields in the striate cortex handle input from both eyes?

Answer 30

Each striate cortex (V1) neuron can receive input from both eyes. By the time visual information reaches primary visual cortex, inputs from both eyes are combined. However, cortical neurons usually have a preferred eye.

Question 31

Occular dominance

Answer 31

where a neuron responds more strongly to one eye than the other

Question 32

Simple cells

Answer 32

preference for light or dark bars | a neuron whose receptive field has clearly defined excitatory and inhibi

Question 33

Complex cells

Answer 33

a neuron whose receptive field does not have clearly defined excitatory and inhibitory regions

Question 34

End stopping

Answer 34

cells that prefer bars of light of a certain length

Question 35

Column

Answer 35

a vertical arrangement of neurons within each column all neurons have the same orientation tuning

Question 36

Hypercolumn

Answer 36

a 1-mm block of striate cortex containing "all the machinery necessary to look after everything visual cortex is responsible for

Question 37

Adaptation

Answer 37

a reduction in response caused by continuing simulation

Question 38

Tilt afterffect

Answer 38

the perceptual illusion of tilt(nagib) produced by adapting to a pattern of given orientation

Question 39

Human vision is coded in -________

Answer 39

spatial frequency channels